Nature and location of excited charge-transfer states in porphyrin dimers: Development of preliminary design characteristics for biomimetic solar energy conversion systems

Journal Article · Sat Feb 01 00:00:00 EST 1986 · J. Chem. Phys.; (United States)

DOI:https://doi.org/10.1063/1.450459· OSTI ID:6191192

Petke, J D; Maggiora, G M

The ground and excited electronic states of a magnesium porphyrin--porphyrin (MgP--P) dimer in a variety of geometries have been investigated by ab initio configuration interaction calculations. The lowest four excited singlet states were found to be locally excited monomer-like (..pi.., ..pi..*) states in each geometry, except for dimers in which the macrocycles were constrained to lie within the van der Waals separation. The lowest MgP/sup +/--P/sup -/ radical pair state CT/sub 1/ was found much higher in energy than the lowest (..pi.., ..pi..*) state; CT/sub 1/reverse arrowS/sub 0/ transition energies varied approximately linearly with macrocyclic center-to-center distance, but were only weakly affected by relative macrocyclic orientation. Coordination of the Mg atom by chloride ion was shown to differentially stabilize CT/sub 1/ relative to (..pi.., ..pi..*) states, to the extent that CT/sub 1/ is positioned near or below the lowest (..pi.., ..pi..*) state. Moreover, estimates of the differential stabilization of CT/sub 1/ by a polarizable medium suggest that combined point-charge and medium effects are sufficient to stabilize CT/sub 1/ below the lowest (..pi.., ..pi..*) state in a variety of geometries of the complex.

• Research Organization: Department of Chemistry, University of Kansas, Lawrence, Kansas 66045
• OSTI ID: 6191192
• Journal Information: J. Chem. Phys.; (United States), Vol. 84:3
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
DIMERS
BIOMIMETIC PROCESSES
PORPHYRINS
ELECTRONIC STRUCTURE
CONFIGURATION INTERACTION
EXCITED STATES
PHOTOSYNTHESIS
CARBOXYLIC ACIDS
CHEMICAL REACTIONS
ENERGY LEVELS
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
SYNTHESIS
140505* - Solar Energy Conversion- Photochemical
Photobiological
& Thermochemical Conversion- (1980-)